The problem with building information modeling (BIM) has always been a lack of reality.

On the computer screen, even a just-hatched BIM model can look plenty real, thanks to productivity-enhancing tools rolled out by companies like Autodesk and Graphisoft. To the uninitiated, the newborn might look very similar to a more mature, ready-to-build computer model of a building.

For a building owner or real estate developer, however, the difference is literally worth millions.

The construction-ready BIM model with all the details needed to bolt columns and hang windows is obviously a lot more valuable.

To solve this problem, the design team can just assure the client that "it's all LOD 400": fully specified and ready to fabricate and build. Or maybe it's LOD 500 -- whoa, dude, the ultimate in readiness! -- with all the BIM elements field-verified and checked against conditions at the construction site.

The acronym stands for Level of Development (LOD or LoD), although it originally meant "level of detail." And it's the next big BIM buzzword for architects and engineers.

The human side of BIM

LOD could help with the "human side of BIM," as Laura Handler, director of virtual design and construction (VDC) at Tocci Building Companies explained recently, repeating the adage that BIM is 10 percent technology and 90 percent sociology.* LOD could improve trust and help spread adoption of BIM, Handler believes.

BIM is already mainstream, with adoption exploding from 17 percent in 2007 to 71 percent last year, according to research from McGraw-Hill Construction. But the term and the tool are still unappealing to many building owners. Could LOD take the bleeding edge off BIM?

Coined by Jim Bedrick, FAIA, a BIM expert and principal architect with AEC Process Engineering, "the LOD framework has become a consensus-based standard that is useful for defining, at the assembly and component level, the reliability of information contained in a BIM."

The new LOD specification document was just released a few weeks ago by BIMForum, after incorporating public comments from an April meeting in Miami of the cross-industry group that promotes BIM adoption.

Bedrick, who used to run construction IT for 3Com and Webcor Builders, lists four top reasons that the LOD lingo will help all of us.

First, the design process is a path from vague concepts to precise descriptions, and only the architect (or other author) knows where it stands at any given moment. Using LOD, they can tell us exactly.

Second, BIM imagery might look vague when the design info is highly precise -- and vice versa. Instead of guessing how advanced the design is based on graphic imagery, just ask, "What's the LOD?"

Third, says Bedrick in a recent AECbytes article, like hand drawings, a BIM model can be misinterpreted. A reader can "infer information" that the author did not intend. With the LOD specified, each BIM element is assigned a minimum level of reliability.

Last, it's a team effort. So each BIM element must be used by various people: the architect needs the structural engineer's work, who needs information from a steel detailer, who asks the construction manager for advice, and so on. The LOD framework basically says either 'Yes, your BIM element is ready for your input' or 'No, please hold on.'

Like it or not

Reaction from the big users of BIM has been mixed. Some like the fact that LOD assigns value to information content rather than the graphic image. "The level of graphical appearance doesn't necessarily progress during a project, it may actually go backwards," writes Antony McPhee, a project architect in Australia.

Another benefit may come in the form of increased use of BIM in the construction phase. "Just about every project I work on now has some sort of BIM deliverable beyond documentation," comments Eddie Krygiel, an architect in Kansas City. "If it's a design/build project, the contractor is using the model for takeoffs and clash detection, which actually do require weekly uploads and updates to the LoD."

Krygiel adds that some owners, including federal and state agencies, want to use their BIM models for asset management and facilities operations. LOD 500 achieves that purpose -- and BIM can be used to track assets that aren't attached to the building model, such as tools, furniture and vehicles.

"One of the most talked about topics around BIM is always LOD," Stephen Hamil of the software company NBS wrote last month.

He explains that it shouldn't be thought of as graphical sophistication but rather "a combination of the detail (the graphical content) and the information (the non-graphical content)."

Bring on the BIM robots

The new LOD specs for BIM will help expand how the technology is used by project teams, not just architects and engineers. For example, if contractors and fabricators use BIM, they can automate the manufacture of building components. LOD 400 BIM elements are, by definition, suitable for computerized fabrication and assembly.

While 95 percent of architects now create 3D models, only a little more than 75 percent of structural, mechanical and electrical subcontractors do the same, according to Steve Jones, director of research at McGraw Hill Construction. This suggests a widening market for BIM-built components and assemblies.

It also foretells a highly collaborative world where designing, manufacturing and building are all interrelated. And that's where LOD becomes essential. With a simple email nod that the BIM model element is LOD 350, for example, the production team knows it's not ready for the assembly line.